Curious About Life: Interview with Roger Summons

Roger Summons is one of the scientists that uses the Curiosity rover to search for biosignatures on Mars. Credit: MIT

The Mars Science Laboratory Curiosity rover has 10 science instruments, and each will be used in the coming weeks and months to help characterize the environment of Mars and determine if the planet ever had the potential for life. The Sample Analysis at Mars (SAM) instrument is actually a combination of three individual instruments that will investigate the chemistry of the Martian surface. Roughly the size of a microwave oven, SAM will analyze samples taken by the robotic arm, looking for organic and inorganic compounds.

Roger Summons, of the Massachusetts Institute of Technology, is working with SAM to study potential organic material within the rocks of Mars.

What type of research do you usually do?

I study the preservation and the characteristics of organic matter in rocks, because organic matter carries information about the organisms that formed it. For example, on Earth we have organic matter preserved in the form of oil shale and coal. So it’s possible to chemically characterize this material, which is biological in origin, and assign organisms or processes to certain components of the organic matter. In respect to petroleum, which is useful as an exploration tool, you can understand what sort of environment and what sort of organisms went into the material that comprises the material.

The microwave-sized SAM instrument is actually composed of three instruments working together. Here, it is being lifted into the Curiosity rover. Credit: NASA/JPL-Caltech

In very ancient sediment soils, you might learn something about the evolution of microbes by looking at transitions in the composition of organic matter through geological time. One of the prime aims of the MSL mission is to search for organic matter on Mars. That’s why I work on the SAM team. SAM has two mass spectrometers whose purpose is to see if first it can detect organic matter, and secondly, to measure the molecular or isotopic characteristics that might tell us where the organic matter came from. We can ask the question, is it biological or nonbiological?

What sort of work do you do specifically with MSL?

Well, I’m on the SAM team working at JPL. Mostly I’m involved with the quadrupole mass spectrometer and the gas chromatograph. I’m also interested in the tunable laser spectrometer results, because if we do find organic in sediments, then we can use that instrument to observe the carbon isotopic patterns of that material.

I have more of an advisory role on the conduct of certain experiments. I try to have an overview of what else is going on with the mission, particularly the information that pertains to understanding what kinds of rocks are being investigated. The cameras, ChemCam, CheMin, APXS—all of those instruments give you information about the mineralogy and sedimentary environment of the sediments. That is important to deciding what sort of samples would be most prospective for organic carbon analysis.

The layers of Mount Sharp, shown here, will help Curiosity examine the history of Mars as it traverses them. Credit: NASA/JPL-Caltech/MSSS

I should point out that I’m one of something like 400 scientists on this mission, so I just contribute to the discussion and the evaluation and the data coming down, to offer suggestions about what samples are going to be most prospective.

I also have a laboratory component. At MIT, I have a mass spectrometer that serves as a partial analog of the SAM GCMS [the Gas Chromatographer and Quadrupole Mass Spectrometer]. It is fitted with a thermal desorption module that mimics the thermal desorption module that will be used for analysis of Mars soil. With our instrument at MIT, and the help of a post-doctorate fellow there, we are able to conduct analog experiments in real time.

We can take any mineral or Mars analog soil material, spike that material with particular organic compounds or any other substances that might be present on Mars, and do experiments that, partially at least, could mimic what is being done by the same instrument in real time. In this way, we are basically field testing or ground truthing the data that might be coming down from Mars, if we replicate that experiment and get the same result.

How can your work help to answer astrobiology questions?

Well, the principle aim of the mission is to determine if Mars is or was ever habitable. That is a very large question with many, many elements to it. If Mars were habitable in any significant way, we would expect to find organic residues of past life, or the building blocks or biosignatures for life. I mean, basically the research is all about biosignatures.

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